The inventive concepts described herein are generally related to an apparatus for inspecting a passive component having a signal transmission line, and more particularly to an apparatus for determining whether a passive component having a signal transmission line has a defect and determining the location of the defect.
Passive components generally refer to components that transfer, accumulate or consume power supplied from other components connected thereto. Passive components typically do not actively amplify or rectify supplied power. A surface-mounted device (SMD)-type element having a width and a height, such as an inductor or a capacitor mounted on a surface of a printed circuit board (PCB), is typically employed as a passive component in a low frequency band. However, since the width and the height of an SMD-type element may tend to exert influence on the inductance or capacitance of the SMD-type element when employed in a high frequency band such as a radio frequency (RF) band, the SMD-type element my have an actual inductance or capacitance value different from its designed value.
Accordingly, instead of an SMD-type element, a signal transmission line, e.g., a microstrip embedded in a PCB, may be employed as a passive component in the RF band. A passive component consisting of a signal transmission line, e.g., an RF passive component, may be manufactured to have a desired inductance or capacitance by embedding the signal transmission line in the PCB in various shapes. Examples of passive components that are made of shaped embedded signal transmission lines include a meander inductor, a spiral inductor, a rectangular shunt capacitor and a fan-shaped shunt capacitor respectively illustrated in FIGS. 6(a) to 6(d. 
However, since a thickness of a signal transmission line embedded in a PCB may be limited, the signal transmission line may be subjected to deformation or defects during the fabrication. When such a defect occurs in an RF passive component, an actual impedance of the RF passive component may be different from an intended impedance, thereby compromising system efficiency of a circuit employing the defective RF passive component. It has thus become necessary and desirable to inspect RF passive components after fabrication to determine whether the signal transmission line forming the RF passive component has any defects.
Conventionally, an X-ray inspection method has been used for such purposes. An X-ray inspection method is typically performed by irradiating X-rays onto a fabricated RF passive component, acquiring an X-ray image of the RF passive component, visually inspecting the RF passive component with an unaided eye based on the acquired image, and then intuitively determining without the benefit of any scientific measure whether the signal transmission line has any defects.
Consequently, conventional X-ray inspection methods take an excessively long time, and are often inaccurate since visual inspection is performed with an unaided eye.
Therefore, there has been a need to develop an apparatus capable of inspecting a passive component having a signal transmission line efficiently and accurately.